Hi Screamer, thank you for your comments.
My weight is close to 90kg and the strong winds in the place were I live are almost always not steady. Those two variables, as also Olah H mentioned, are the main reason to buy the 79 instead of a smaller board.
I'll problably lose some fun in the 3.5m-4.0m wind range due to this choice, but such epic days are very very rare in my country.